It is well known that a golfer's game is greatly affected by the golf clubs used. For this reason golfers spend considerable time in selecting the golf clubs that is best suited to their techniques of play. Furthermore, an individual's golf swing may vary slightly or dramatically from week to week, and the golfer is limited to his or her clubs that were selected based on his or her swing at a given point in time.
Among the factors that a golfer considers in selecting a set of clubs are its swing weights, weight distribution of the club head and the center of gravity of the club. These same criteria are considered by golf club manufacturers in their unsuccessful efforts to customize their product to satisfy individual requirements. However, because clubs are designed for esthetics rather than the individual golfer's needs and abilities, it has not been feasible to find or assemble a set of clubs which matches any one individual golfer's psychological, physical and skill requirements perfectly all the time.
Consequently, most of the commercially available clubs are weighted within a narrow range so that they can be used by the vast majority of golfers. As a result, a very small adjustment in the weight of the club is needed to change the center of gravity and the total weight of the club head.
It is well known that the weight of the golf club affects the speed of swing that in turn controls the distance of a shot. The faster the speed of the club head at the time of impact with the ball, the longer the length of a shot will result. The club head speed is governed by the strength of the player and the weight of the club head. For a given player, the weight of a club head is; therefore, the governing factor for obtaining the maximum possible distance.
Unfortunately, there is no way to adjust the weight of a club short of buying a new set of clubs. For example, the club designed for six feet five-inch tall person is also used by a player with much less stature and strength. This is particularly true with the clubs intended for juniors, and in some extent seniors and women players. The golf clubs are, for the most part, made for one "standard" and "average" person. Moreover, the strength of a golfer may change as he or she gets older, and weighing of the club will need to change also. The advantage of adjustability of the club to suit each player's need becomes obvious. The subject invention addresses a method to adjust the total clubhead weight of a given club based on a player's physical characteristics and skill level to achieve the best possible golf shots.
Similarly, the location of the center of gravity of a club head has a significant effect on the driving characteristics of a golf shot, particularly with less skilled and less experienced golfers. Location of the center of gravity for a club is very important since it can control the trajectory of the ball. Unlike an expert who can control the flight of the ball by controlled rotation of his hands to cause a spin to be imparted to the ball, a less skilled golfer relies on attempting to hit the ball so that impact with the club head is made at the sweet spot that is generally located along a vertical line which runs directly opposite the center of gravity of the head. A small change in the center of gravity can influence the tendency of a shot to hook or slice. A golf shot can hook or slice depending on the training and acquired habits of a player. If an adjustment of the center of gravity of a club is possible, the tendency of hooking or slicing a shot may be compensated by making a small change of the center of gravity without modifying the swing. Some manufacturer varies the center of gravity according to the loft of the club. Nevertheless, no club design allows adjustment of the center of gravity for a given club. This invention addresses a method of adjusting the center of gravity of a given club.
Another important feature in the construction golf club's club head is the distribution of weight. Depending on the weight distribution, a golf club can influence the distance of a shot and tendency to hook or slice the ball for a given skill level of a player. Therefore, a manufacturer will design the clubs adjusted to the skill of a player. For example, an iron designed for a skilled player usually has most of the weight centered behind the optimal hitting area on the club surface, or sweet spot. However, this type of club does not offer much margin for error. For majority of players, the manufactures offer other designs mainly depending on how the weight is distributed. A perimeter-weighted, heel-toe weighted, or sole-weighted irons are some typical examples. The perimeter-weighted clubs have a larger sweet spot, allowing more margin for error. Since all the weight does not have to be centered directly behind the sweet spot for a good shot to come off, distributing the club head's weight around the perimeter will help to compensate for a mis-hit. Other manufactures distribute the majority of the weight in the heel and toe of the clubhead, book ending the sweet spot. The theory is that less-skilled players mis-hit most of their shots in the heel or toe, so when they do, the weight is there to compensate. Furthermore, some clubs have a high concentration of weight toward the sole of the club. Locating the majority of clubhead's weight under the equator of the ball, a player will have easier time to get the ball airborne. In the case of putters, most putters are heel-toe weighted, with very little weight directly behind the ball. All these clubs mentioned above have fixed weight distribution, and there is no way to change the original design. Only commercially available method to modify the weight distribution is to attach a strip of thin tape made with lead.
In the past, many prior art proposals have been made for weight adjustment and, accordingly, the customizing of a golf club to one's swing has been made. For example, U.S. Pat. No. 5,297,794 to Lu discloses club head with weight furnishing 20 to 25 percent of the club head mass. This proposal lacks any feature of adjusting weight distribution, and more importantly, in practical purposes, it is not necessary to change such a large percentage of weight to achieve the desired purpose.
Other golf clubs with adjustable weighing representative of the prior art are disclosed in U.S. Pat. Nos. 4,607,846 to Perkins, 5,385,348 to Wargo, and 4,869,507 to Sahm. These patents all provide adjustable swing weight and weight distribution. The U.S. Pat. No. 4,607,846 provides two elongated openings extending directionally between the toe and heel with threaded weights. This arrangement appears to satisfy the adjustability requirement of both total club head weight and weight distribution. However, it is too complicated in design to apply to practical uses. The U.S. Pat. No. 5,385,348 and No. 4,869,507 have provisions for one or more replaceable inserts of varying weight to adjust the total weight and weight distribution of a club. Although elegant, it lacks simplicity and infinitely adjustable features of the subject invention.
There have been other attempts to add the adjustable weight feature to a golf club head, mainly to a wood type golf club in the prior patent art. For example, U.S. Pat. No. 5,013,041 to Sun shows a wood type golf club which has a pair of parallel longitudinal chambers placed behind the face plate. By placing a set of weight members in the chamber, the club head weight and the center of gravity of the club may be varied. U.S. Pat. No. 5,518,243 to Redman features a weight distributor which includes an array of apertures to receive spherical weights. Although both of these prior art permit change of club head weight and center of gravity, they apply only to the wood type of golf club and lack simplicity and infinitely an adjustable feature of the subject invention.
There have been many other attempts to add weight adjustment features to a golf club head, particularly to a putter head. Bushner U.S. Pat. No. 4,895,371; Anderson U.S. Pat. No. 4,962,932; Au U.S. Pat. No. 5,244,210; and Bland U.S. Pat. No. 5,688,189 are some of the examples. However, all these prior arts are for the putter type of golf club, and lack universal applicability to other type of golf clubs such as iron, wood and wedge.